You configured it by yourself or anyone else? Since you cannot login with support/support, you'd better restore your device to facotry defaults and reconfigure it. Later, try support again. If it...

td w8961nd has no bandwidth control feature. You may explain what you are trying to do indeed and someone may reply you if this modem can do it or not.

TD-W8960N V5 supports inconsistant external and internal port. The port 80 is used by w8960 itself and it cannot be modified but you can solve it as Giangi mentioned in the end.

WR841N should be OK. Suggest purchasing WR841N V9 which is the latest version. :)

Your router is WA901ND? Actually, it is not a router. Is it connecting to a modem or a router? If it is a modem, is it a cable modem or ADSL modem? Are you trying to share internet wirelessly by...

What is WLAN port? Do you mean WAN port? WAN port should be connected to your modem instead of PC. To access internet, you should connect clients to LAN ports or connect to WR740N wirelessly.